[pct-l] personal locator beacons

[Fred Walters]

I actually looked into this, both here (PCT-L) and with my phone
manufacturer - and both agreed that most smartphones do not require
GSM/xG/data service to give you a position.

Most Smartphones use aGPS and my understanding was that aGPS (on
Smartphones) uses the data connection (WiFi or GSM) to periodically
download data that speeds up the GPS system giving you a position fix.  The
downloaded data is often downloaded daily and will become useless after a
few days to a week.  This aGPS data speeds-up the fix and without it (i.e.
without a data connection) you will still get a position, just it will take
a lot longer to get that position.

I understand phones can also use the carrier cellular system to get an
approximate position from masts (but in my experience (in UK) this is so
inaccurate as to be worthless when out hiking.

When I asked the manufacturer (directly) they responded:
*"Thank you for contacting the xxxxxxx support centre regarding the GPS on
your Sony Xperia Sola handset.

We can confirm that the GPS on the handset will work without any network
coverage or Wi-Fi/3G connection. In order for this to access GPS satellites
without any network coverage, you must be outdoors however you may find
that the GPS connection is slower without any coverage.

You can test this on your **xxxxxxx** handset by removing the SIM card,
standing outside and following these steps:

1. Dial yyyyyyyyyyyyy**
2. Select Service Tests.
3. Select GPS.
4. Select GPS Location test.

The handset will then use GPS satellites to determine your location.
**
We hope this infromation has been helpful to you."*

I've blanked out the manufacturer but having done that am unsure quite why
'cos it's not confidential.  Sony Xperia Sola Android if anybody wants the
magic details let me know.

Whilst not all smartphones use the same hardware I suspect most provide
comparable functionality.


On Mon, Mar 4, 2013 at 9:25 PM, Dennis Phelan <dennis.phelan at gmail.com>wrote:

> However if you don't have cell service i don't believe the GPS
> functionality works and therefore you don't see the nice little flashing
> spot that tells you where you are on the trail.  However you do have a nice
> map that does show the trail and the mile markers.
>
> Dennis
>
>
> On Mon, Mar 4, 2013 at 1:07 PM, Ed Jarrett <edjarrett at msn.com> wrote:
>
> > Cell service is not required for Backcountry Navigator if you pre-cache
> > the maps or just load the map set upfront.
> >
> > Ed Jarrett Blog: http://aclayjar.blogspot.com/  Twitter:
> > https://twitter.com/EdJarrett53 Facebook:
> > https://www.facebook.com/ed.jarrett.71
> >
> > > Date: Mon, 4 Mar 2013 12:13:38 -0800
> > > From: rgraybill44 at gmail.com
> > > To: srhspaded at yahoo.com
> > > CC: pct-l at backcountry.net
> > > Subject: Re: [pct-l] personal locator beacons
> >
> > > On the other hand, if you use the *Backcountry Navigator* app (which
> has
> > no
> > > relationship to Delorme's *inReach*), download the PCT waypoints to it,
> > > turn on your smartphone's location services, and happen to have a
> > > connection to your service provider's network, then you can see quite
> > > precisely where you are and that you're still on the trail. And at many
> > > points along that 20 miles stretch, I did have cell phone service,
> > > sometimes even 4G, so I could use *Backcountry Navigator*.
> >
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